A multi-stage gearbox having nine forward gears and one reverse gear is known from DE 10 2008 000 429 A1. The multi-stage gearbox includes four planetary sets, eight rotatable shafts and six shift elements. The first and the second planetary set form a shiftable upstream gear set, whereas the third and the fourth planetary sets constitute a main gear set. The planetary carriers of the first and second planetary sets are coupled to one another by one of the rotatable shafts, which is connected to an element of the main gear set. The ring gear of the first planetary set is coupled to the sun gear of the second planetary set by a further shaft of the rotatable shafts, which is detachably connectable by a clutch to a drive input shaft.
The sun gear of the first planetary set is couplable via a further shaft of the rotatable shafts to a housing of the multi-stage gearbox by a brake and is connectable by a clutch to the drive input shaft. The ring gear of the second planetary set is couplable via a shaft to the housing by a brake. In turn, a further shaft of the rotatable shafts is connected at least to one element of the main gear set and is couplable by the brake to the housing. A further shaft of the rotatable shafts is connected to a further element of the main gear set and is connectable to the drive input shaft by a shift element in the form of a clutch, whereas a drive output shaft is connected to at least one further element of the main gear set. At least two of the shift elements of the multi-stage gearbox are in the form of positively engaging shift elements, which are deactivated only during upshifts.
To save fuel, aside from so-called start-stop systems, vehicles are also increasingly being equipped with so-called sailing functions, by which, during travel, an internal combustion engine is shut down and decoupled from the rest of the drivetrain. When a sailing operating function of said type is active, the existing kinetic energy of a motor vehicle is utilized for forward motion rather than being lost in the form of drag losses. In hybrid vehicles, this sailing operating function is already widely used, though the sailing function is increasingly also being used in conventional motor vehicles with internal combustion engines. By contrast to start-stop systems in which the engine is shut down only when a vehicle is at a standstill, it is provided in the case of an active sailing operating function that an engine in the form of internal combustion engine is shut down already during a coasting operating state of a vehicle, the gearbox then having to be supplied with hydraulic fluid by an electrical auxiliary pump, which however increases both a structural space requirement and the production costs of a gearbox.